During the manufacture of corn-based snack chips, such as tortilla chips, raw corn is subjected to a number of processing steps prior to being fried into the final product. Typically, these steps consist of (1) cooking in water, (2) soaking in water (the water containing a relatively small amount of lime for maintenance of pH), (3) washing the cooked and soaked corn to remove non-corn debris, corn husks, small pieces of corn, etc., (4) milling the washed corn and (5) extruding or shaping the milled corn into the desired shape prior to frying. This process has been perfected over a period of years, with the only remaining serious defect in the process arising during the washing of the corn. With currently available technology, the corn washing results in damaged corn and uneven quantities of corn leaving the washer and entering the milling unit, known as "surge".
Typical corn washing units in use today consist of a receiver portion and a hopper portion. The corn washer receiver receives the corn/water slurry from the soak unit under pressure, and is designed to minimize damage to the corn by decelerating the corn slurry prior to its entry into the corn washer hopper. The corn washer receiver currently in widespread use is relatively simple and generally maintenance free, but has several design deficiencies which lead to surging and lower yield (because of corn damage). An apparatus designed to alleviate these problems is a corn washer unit designed by HyCor Corporation and manufactured under the trade name "Rotostrainer". This device decelerates the corn slurry from the soak unit and dewaters the corn prior to depositing the corn in a corn washer. The dewatering action of this unit is accomplished by passing the corn slurry over a rotating screen drum so that the water drains through the screen while the corn is retained thereon. As the drum continues rotating, the corn eventually falls into the corn washer hopper. The design of the Rotostrainer is intended for use in a continuous operation--the capacity is insufficient for use in a batch process where large quantities of slurry are deposited on the dewatering device at one time. While this device performs well in its intended function, the cost (on the order of 10 to $15,000) and complexity induced applicants to design a simpler, less expensive unit.
An object of the present invention is to provide a means of decelerating the corn-water slurry as it enters the corn washer hopper so that less damage to the corn, which is very soft from cooking and soaking, would result. The damaged or broken corn, being substantially smaller in size than normal corn kernels, is lost in the corn washer (exiting with the wash water), thereby resulting in lower process yields. Broken corn that is retained in the washer and which moves through the hopper and into the milling unit produces undesirable inconsistencies in the finished product quality, since broken corn contains different amounts of moisture than whole corn, affecting the appearance, texture and oil content of finished corn chips.
A second object of the present invention is to reduce or eliminate corn washer surge that occurs in conventional prior art processes. Because the corn-water slurry is transferred from the soaking unit to the washer in a "batch" mode, the corn exiting the corn washer receiver and entering the corn washer hopper is still primarily in slurry form since little or no water is removed in the receiver. The takeout auger at the bottom of the hopper is designed to meter a controlled amount of corn (with whatever residual water is not separated there from) to a final corn washer unit and then to the milling unit. When a new load of corn-water slurry is delivered to the corn washer hopper from the receiver, a substantial amount of water necessarily flows into the auger unit and carries corn with it. Because this corn is prematurely removed from the corn washer hopper, it creates a momentary overload on the corn washer and thus is not cleaned as well as washed corn not carried through the washer in a surge. Also, the excess corn in the auger results in extra corn being delivered to the milling unit, resulting in inconsistent final product. Therefore, there is a need for a low cost, low maintenance corn dewatering device which will deliver uniformly clean corn to a milling unit at a uniform rate.